Load Signal Test - Code 31

Disconnect 16-pin connector. Turn ignition switch to "ON" and measure voltage between terminal No. 22 and ground when any of the following load switches are turned on: power steering oil pressure switch, heater/air conditioner switch, headlamp switch, rear defogger switch, or radiator fan switch. Battery voltage should be present. If ok, replace the ECU. If not okay, check load system operation, and the harness between ECU and diodes, and harness between diodes and switches. If not okay, replace/repair. If okay, replace ECU.